561778551 has 8 divisors (see below), whose sum is σ = 832264560. Its totient is φ = 374519016.

The previous prime is 561778543. The next prime is 561778561. The reversal of 561778551 is 155877165.

561778551 is a `hidden beast` number, since 561 + 7 + 7 + 85 + 5 + 1 = 666.

It is not a de Polignac number, because 561778551 - 2³ = 561778543 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 561778497 and 561778506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561778561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10403280 + ... + 10403333.

It is an arithmetic number, because the mean of its divisors is an integer number (104033070).

Almost surely, 2^561778551 is an apocalyptic number.

561778551 is a deficient number, since it is larger than the sum of its proper divisors (270486009).

561778551 is a wasteful number, since it uses less digits than its factorization.

561778551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20806622 (or 20806616 counting only the distinct ones).

The product of its digits is 294000, while the sum is 45.

The square root of 561778551 is about 23701.8680909333. The cubic root of 561778551 is about 825.1287468493.

The spelling of 561778551 in words is "five hundred sixty-one million, seven hundred seventy-eight thousand, five hundred fifty-one".